The Effect of Electromyographic Jitter on Single Motor Unit EMG Potentials

1979 ◽  
Vol BME-26 (8) ◽  
pp. 471-478 ◽  
Author(s):  
D. C. Boyd ◽  
Peter D. Lawrence ◽  
Paul J. A. Bratty
Keyword(s):  
Motor Unit ◽  
Single Motor Unit ◽  
Single Motor ◽  
Motor Unit Emg

Rectification is required to extract oscillatory envelope modulation from surface electromyographic signals

2014 ◽  
Vol 112 (7) ◽  
pp. 1685-1691 ◽  
Author(s):  
Christopher J. Dakin ◽  
Brian H. Dalton ◽  
Billy L. Luu ◽  
Jean-Sébastien Blouin
Keyword(s):  
Motor Unit ◽  
Stimulus Frequency ◽  
Motor Units ◽  
Surface Emg ◽  
Medial Gastrocnemius ◽  
Single Motor Unit ◽  
Single Motor ◽  
Single Motor Units ◽  
Emg Signal ◽  
Envelope Modulation

Rectification of surface electromyographic (EMG) recordings prior to their correlation with other signals is a widely used form of preprocessing. Recently this practice has come into question, elevating the subject of EMG rectification to a topic of much debate. Proponents for rectifying suggest it accentuates the EMG spike timing information, whereas opponents indicate it is unnecessary and its nonlinear distortion of data is potentially destructive. Here we examine the necessity of rectification on the extraction of muscle responses, but for the first time using a known oscillatory input to the muscle in the form of electrical vestibular stimulation. Participants were exposed to sinusoidal vestibular stimuli while surface and intramuscular EMG were recorded from the left medial gastrocnemius. We compared the unrectified and rectified surface EMG to single motor units to determine which method best identified stimulus-EMG coherence and phase at the single-motor unit level. Surface EMG modulation at the stimulus frequency was obvious in the unrectified surface EMG. However, this modulation was not identified by the fast Fourier transform, and therefore stimulus coherence with the unrectified EMG signal failed to capture this covariance. Both the rectified surface EMG and single motor units displayed significant coherence over the entire stimulus bandwidth (1–20 Hz). Furthermore, the stimulus-phase relationship for the rectified EMG and motor units shared a moderate correlation ( r = 0.56). These data indicate that rectification of surface EMG is a necessary step to extract EMG envelope modulation due to motor unit entrainment to a known stimulus.

scholarly journals An Analysis or the single Motor Unit Activity Involved in Oro-facial Functions

1986 ◽  
Vol 4 ◽  
pp. 115-122
Author(s):  
Hideho Handa ◽  
Yukihiro Fujita ◽  
Yasuyo Nomora ◽  
Hiroshi Suzuki ◽  
Kazuo Toda ◽  
...  
Keyword(s):  
Motor Unit ◽  
Unit Activity ◽  
Single Motor Unit ◽  
Single Motor ◽  
Motor Unit Activity

EMG Changes in Human Thenar Motor Units With Force Potentiation and Fatigue

2006 ◽  
Vol 95 (3) ◽  
pp. 1518-1526 ◽  
Author(s):  
C. K. Thomas ◽  
R. S. Johansson ◽  
B. Bigland-Ritchie
Keyword(s):  
Motor Unit ◽  
Motor Units ◽  
Emg Activity ◽  
Single Motor Unit ◽  
Tetanic Force ◽  
Twitch Force ◽  
Emg Amplitude ◽  
Before And After ◽  
Induced Changes ◽  
Motor Unit Emg

Few studies have analyzed activity-induced changes in EMG activity in individual human motor units. We studied the changes in human thenar motor unit EMG that accompany the potentiation of twitch force and fatigue of tetanic force. Single motor unit EMG and force were recorded in healthy subjects in response to selective stimulation of their motor axons within the median nerve just above the elbow. Twitches were recorded before and after a series of pulse trains delivered at frequencies that varied between 5 and 100 Hz. This stimulation induced significant increases in EMG amplitude, duration, and area. However, in relative terms, all of these EMG changes were substantially smaller than the potentiation of twitch force. Another 2 min of stimulation (13 pulses at 40 Hz each second) induced additional potentiation of EMG amplitude, duration, and area, but the tetanic force from every unit declined. Thus activity-induced changes in human thenar motor unit EMG do not indicate the alterations in force or vice versa. These data suggest that different processes underlie the changes in EMG and force that occur during human thenar motor unit activity.

Fractionation of the motor unit: response to tetanus

1961 ◽  
Vol 200 (4) ◽  
pp. 689-693
Author(s):  
Simeon Locke
Keyword(s):  
Action Potential ◽  
Motor Unit ◽  
Nerve Terminal ◽  
Differential Effect ◽  
Blocking Agent ◽  
Single Motor Unit ◽  
Single Motor ◽  
Blocking Agents ◽  
Before And After ◽  
Post Tetanic Potentiation

The effect of a tetanus on the motor unit of the gastrocnemius of the rat has been studied before and after administration of blocking agents. Post-tetanic potentiation of action potential of the single motor unit occurs following depression of response by curare or decamethonium. Increased amplitude of unit potential results from partial resynchronization of subunit potential contributions which had been desynchronized by the differential effect of the blocking agent on subunit latency. Decline of unit potential subsequent to post-tetanic potentiation results from desynchronization of component contributions as had been observed with initial administration of blocking agent. The occurrence of these events in a single motor unit indicates that they take place at the nerve terminal or subterminal portion of the unit.

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